Soft robotic actuator enhancements

ABSTRACT

Exemplary embodiments provide enhancements for soft robotic actuators. In some embodiments, angular adjustment systems are provided for varying an angle between an actuator and the hub, or between two actuators. The angular adjustment system may also be used to vary a relative distance or spacing between actuators. According to further embodiments, rigidizing layers are provided for reinforcing one or more portions of an actuator at one or more locations of relatively high strain. According to further embodiments, force amplification structures are provided for increasing an amount of force applied by an actuator to a target. The force amplification structures may serve to shorten the length of the actuator that is subject to bending upon inflation. According to still further embodiments, gripping pads are provided for customizing an actuator&#39;s gripping profile to better conform to the surfaces of items to be gripped.

RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 14/944,999, filed Nov. 18, 2015, which is acontinuation-in-part of U.S. patent application Ser. No. 14/857,648,filed on Sep. 17, 2015 and entitled “Soft Robotic Actuator AttachmentHub and Grasper Assembly, Reinforced Actuators, and ElectroadhesiveActuators.” The present application also claims priority to U.S. PatentApplication Ser. No. 62/081,323, filed on Nov. 18, 2014 and entitled“Soft Robotic Actuator Enhancements,” the contents of which areincorporated herein by reference.

FIELD OF THE DISCLOSURE

The disclosure relates generally to the field of robotics andparticularly to hubs and assemblies for interfacing soft roboticactuators with another mechanical system, and to enhancements for softrobotic actuator systems.

BACKGROUND

Robotics are used in many industries, such as industrial applications(e.g., manufacturing and packaging), medical applications, and the like.Soft robotics is a developing area of robotics that provides soft,conformal, and adaptive graspers and actuators to enable robots tointeract with objects in a more adaptive manner than in traditionalrobotics. For example, a single grasper may adapt to the size, weight,and shape of varying objects in each task, just as the human hand can.

A magnetic assembly to combine “hard” and “soft” robotics has beendisclosed in A Hybrid Combining Hard and Soft Robotics, Stokes Adam A.,Shepherd Robert F., Morin Stephen A., Ilievski Filip, and WhitesidesGeorge M., Soft Robotics. March 2014, 1(1): 70-74.doi:10.1089/soro.2013.0002, which article is incorporated herein byreference in its entirety. However, the proposed combination of hard andsoft robotics does not provide the versatility necessary to operatesimilar to a human.

The present disclosure is directed to the above, and other, limitationsof existing systems. In particular, the present disclosure providesimprovements in interfacing hard and soft robotics and also providesimproved actuators.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an exemplary embodiment of ahub assembly and soft robotic actuators in accordance with variousexamples of the present disclosure.

FIGS. 2A-2C are exploded views of the hub assembly of FIG. 1.

FIGS. 3A-3E are assembled views of the hub assembly and soft roboticactuators of FIG. 1.

FIGS. 4A-4D are perspective views illustrating an exemplary twist lockinterface for the hub assembly of FIG. 1.

FIGS. 5A-5C are perspective views illustrating an example grasper usingthe hub assembly of FIG. 1 and soft actuators having mechanical orelectro-mechanical portions.

FIGS. 6A-6D are perspective views illustrating a grasper using the hubassembly of FIG. 1 and soft actuators having a configurable angle ofattack.

FIGS. 7A-7E are perspective view depicting a soft robotic actuatorassembly having a plurality of angularly adjustable gripping actuatorsand a plurality of adjusting actuators for adjusting the angle of attackof the gripping actuators.

FIGS. 8A-8F depict exemplary reinforcement structures for reinforcing asoft actuator.

FIGS. 9A and 9B are perspectives view depicting an exemplary reinforcinglayer.

FIG. 10A is a perspective view depicting a soft robotic actuatorassembly having a plurality of actuators surrounded by a forceamplification band.

FIG. 10B is a perspective view depicting a soft robotic actuatorassembly having a plurality of actuators surrounded by an automaticallyadjustable force amplification band.

FIG. 10C is a perspective view depicting an exemplary figure-8 forceamplification band.

FIGS. 11A-11F are side views illustrating soft robotic actuatorsprovided with various exemplary gripping pads, textures, and tools.

SUMMARY

According to exemplary embodiments, angular adjustment systems areprovided for varying an angle between an actuator and the hub, orbetween two actuators. The angular adjustment system may also be used tovary a relative distance or spacing between actuators. Such a systemallows for a robotic manipulator to be dynamically adjusted without theneed to replace the individual actuators or the entire manipulator.Accordingly, a manipulator can be varied to grasp objects of differentsizes and shapes.

According to further embodiments, rigidizing layers are provided forreinforcing one or more portions of an actuator. In some cases,reinforcements may be placed at areas of relatively high strain, whichmay help to prevent premature failure of the actuator. For example,laces may be provided for preventing certain regions from expanding. Inother situations, reinforcement can be used to prevent the base wall ofthe actuator from bending away from the neutral bending plane, whichallows the actuator to bend more effectively. In both cases, theactuator may be capable of accommodating higher inflation pressures. Athigher inflation pressures, more force can be applied to a target.

According to further embodiments, force amplification structures areprovided for increasing the amount of force applied by an actuator to atarget. In some embodiments the force amplification structures serves toshorten the length of the actuator utilized when gripping an object.Since more force is required to deflect a shorter actuator an equaldistance as a longer actuator of the same cross section, shortening theactuator through the use of a force amplification structure has theeffect of increasing the force required to deflect the actuators of agripper when grasping a given target object. The higher force requiredto deflect the shorter fingers during gripping yields a higher gripforce applied to the target object than what would be given by theeffectively longer actuators that are not reinforced by a forceamplification structure. Moreover, the force amplification structuresmay stabilize the actuator(s) against twisting and overlapping.

According to further embodiments, gripping pads are provided forcustomizing an actuator's gripping profile to better conform to thesurfaces of items to be gripped. The gripping pads may have a texturedsurface that may be added to, or built into (e.g., by molding) theactuator(s). An individual actuator may include multiple different padsthat each contact a gripped item in a desired manner or in a desiredlocation.

These and other advantages of the exemplary embodiments will be apparentfrom the detailed description below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. The invention, however, may be embodied inmany different forms and should not be construed as being limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thedrawings, like numbers refer to like elements throughout.

Multiple enhancements to soft actuators and actuator hub assemblies arediscussed herein. For ease of discussion, each of these concepts isdescribed below in separate sections. However, it is to be understoodthat the embodiments described herein may be used together in anycombination in order to achieve the benefits described herein.

A general overview of a soft robotic system in which the above-notedenhancements may be employed is now described with reference to FIGS. 1through 5C.

System Overview

Conventional robotic grippers or actuators may be expensive andincapable of operating in certain environments where the uncertainty andvariety in the weight, size and shape of the object being handled hasprevented automated solutions from working in the past. The presentapplication describes applications of novel soft robotic actuators thatare adaptive, inexpensive, lightweight, customizable, and simple to use.

Soft robotic actuators may be formed of elastomeric materials, such asrubber, or thin walls of plastic arranged in an accordion structure thatis configured to unfold under pressure, or other suitable relativelysoft materials. They may be created, for example, by molding one or morepieces of the elastomeric material into a desired shape. Soft roboticactuators may include a hollow interior that can be filled with a fluid,such as air, water, or saline to inflate and actuate the actuator. Uponactuation, the shape or profile of the actuator changes. In the case ofan accordion-style actuator (described in more detail below), actuationmay cause the actuator to curve or straighten into a predeterminedtarget shape. One or more intermediate target shapes between a fullyunactuated shape and a fully actuated shape may be achieved by partiallyinflating the actuator. Alternatively or in addition, the actuator maybe actuated using a vacuum to remove inflation fluid from the actuatorand thereby change the degree to which the actuator bends and/orextends.

Actuation may also allow the actuator to exert a force on an object,such as an object being grasped or pushed. However, unlike traditionalhard robotic actuators, soft actuators maintain adaptive properties whenactuated such that the soft actuator can partially or fully conform tothe shape of the object being grasped. Furthermore, the amount of forceapplied can be spread out over a larger surface area in a controlledmanner because the material can easily deform. In this way, soft roboticactuators can grip objects without damaging them.

Moreover, soft robotic actuators allow for new types of motions orcombinations of motions (including bending, twisting, extending, andcontracting) that can be difficult or impossible to achieve withtraditional hard robotic actuators.

In accordance with the present disclosure, a hub and/or grasper assemblyfor interfacing soft robotic actuators with hard robotic assemblies isprovided. Additionally, new configurations and types of actuators aredescribed. The actuators may be used with the hub and/or grasperassembly.

An actuator may be a soft robotic actuator, which is inflatable with aninflation fluid such as air, water, or saline. The inflation fluid maybe provided via an inflation device through a fluidic connection. Theactuator may be in an uninflated state in which a limited amount ofinflation fluid is present in the actuator at substantially the samepressure as the ambient environment. The actuator may also be in a fullyinflated state in which a predetermined amount of inflation fluid ispresent in the actuator (the predetermined amount corresponding to apredetermined maximum force to be applied by the actuator or apredetermined maximum pressure applied by the inflation fluid on theactuator). The actuator may also be in a full vacuum state, in which allfluid is removed from the actuator, or a partial vacuum state, in whichsome fluid is present in the actuator but at a pressure that is lessthan the ambient pressure. Furthermore, the actuator may be in apartially inflated state in which the actuator contains less than thepredetermined amount of inflation fluid that is present in the fullyinflated state, but more than no (or very limited) inflation fluid.

In the inflated state, the actuator may curve around a central axis. Forease of discussion, several directions are defined herein. An axialdirection passes through the central axis around which the actuatorcurves. A radial direction extends in a direction perpendicular to theaxial direction, in the direction of the radius of the partial circleformed by the inflated actuator. A circumferential direction extendsalong a circumference of the inflated actuator.

In the inflated state, the actuator may exert a force in the radialdirection along the inner circumferential edge of the actuator. Forexample, the inner side of the distal tip of the actuator exerts a forceinward, toward the central axis. The soft robotic actuator may remainrelatively conformal when inflated, due to the materials used and thegeneral construction of the actuator.

The actuator may be made of one or more elastomeric materials that allowfor a relatively soft or conformal construction. Depending on theapplication, the elastomeric materials may be selected from a group offood-safe, biocompatible, or medically safe, FDA-approved materials. Theactuator may be manufactured in a Good Manufacturing Process(“GMP”)-capable facility.

The actuator may include a base that is substantially flat. The actuatormay also include one or more accordion extensions. The accordionextensions allow the actuator to bend or flex when inflated, and help todefine the shape of the actuator when in an inflated state. Theaccordion extensions include a series of ridges and troughs. The size ofthe accordion extensions and the placement of the ridges and troughs canbe varied to obtain different shapes or extension profiles.

By changing the shape of the body of the actuator, or the size,position, or configuration of the accordion extensions, different sizes,shapes, and configurations may be achieved. Moreover, varying the amountof inflation fluid provided to the actuator allows the actuator to takeon one or more intermediate sizes or shapes between the un-inflatedstate and the inflated state. Thus, an individual actuator can bescalable in size and shape by varying inflation amount, and an apparatusincluding an actuator can be further scalable in size and shape byreplacing one actuator with another actuator having a different size,shape, or configuration.

The actuator extends from a proximal end to a distal end. The proximalend may optionally connect to an interface. The interface allows theactuator to be releasably coupled to other parts of the hub assembly.The interface may be made of stainless steel, aluminum, plastic, or afood-safe or medically-safe material, such asAcrylonitrile-Butadiene-Styrene (“ABS”) or Delrin. The interface may bereleasably coupled to one or both of the actuator and a fluidicinterface to the hub. The interface may have a port for connecting tothe actuator. Different interfaces may have different sizes, numbers, orconfigurations of actuator ports, in order to accommodate larger orsmaller actuators, different numbers of actuators, or actuators indifferent configurations.

The actuator may be inflated with an inflation fluid supplied from aninflation device through the fluidic connection. The interface mayinclude or may be attached to a valve for allowing fluid to enter theactuator but preventing the fluid from exiting the actuator (unless thevalve is opened). The fluidic connection may also or alternativelyattach to an inflator valve at the inflation device for regulating thesupply of inflation fluid at the location of the inflation device.

The inflation fluid may be, for example, air, water, or saline. In thecase of air, the inflation device may include a bulb or bellows forsupplying ambient air. In the case of saline, the inflation device mayinclude a syringe or other appropriate fluid delivery system.Alternatively or in addition, the inflation device may include acompressor, pump, regulator, or tank of compressed or liquefied gas forsupplying the inflation fluid.

For example, the inflation device may include a fluid supply forsupplying an inflation fluid. In one embodiment, the fluid supply may bea reservoir for storing compressed air or saline, or may be a vent forsupplying ambient air to the fluidic connection.

The inflation device may further include a fluid delivery device, suchas a pump, regulator, or compressor, for supplying inflation fluid fromthe fluid supply to the actuator through the fluidic connection. Thefluid delivery device may be capable of supplying fluid to the actuatoror withdrawing the fluid from the actuator (e.g., through a vacuum orsimilar operation). The fluid delivery device may be powered byelectricity. To supply the electricity, the inflation device may includea power supply, such as a battery or an interface to an electricaloutlet.

The power supply may also supply power to a control device. The controldevice may allow a user to control the inflation or deflation of theactuator, e.g. through one or more actuation buttons (or alternativedevices, such as a switch). The control device may include a controllerfor sending a control signal to the fluid delivery device to cause thefluid delivery device to supply inflation fluid to, or withdrawinflation fluid from, the actuator.

The above described components may be connected together using a hub.Referring to FIG. 1, an exemplary hub 100 in accordance with the presentdisclosure is shown. The hub 100 includes a master side assembly 10 anda tool side assembly 20. In general, the master side assembly 10 may beconnected or connectable to a mechanical assembly, such as a roboticarm, a robotic gantry system, a robotic manipulator, or in general anyend effector of a robotic (e.g., hard robotics) assembly. The tool sideassembly 20 may be configured to operably connect a number a of varioussoft actuators (where a is a positive integer). In particular, the toolside assembly 20 may be provided with a number b of actuator attachmentportions (where b is a positive number). It is important to note, thatthe tools side assembly 20 may be configured connect any number of softactuators However, for convenience and clarity, a number of softactuators (e.g., 30-1, 30-2, 30-3, and 30-4) and a number of actuatorattachment portions (e.g., 20-1, 20-2, 20-3, and 20-4) are depicted inthe figures. Additionally, it is important to note that the number b ofactuator attachment portions may be different than the number a ofactuators connected to the tool side assembly 20.

In general, each of the master side assembly 10 and the tool sideassembly 20 include an interface configured to releaseably couple theassemblies 10 and 20 to each other. In particular, the tool sideassembly 20 includes an interface portion 21 while the master sideassembly includes an interface portion 11 (obscured by the angle ofviewing). The interface portions 11 and 21 can be configured to couplethe assemblies 10 and 20 and to provide a seal for inflation line (e.g.,pneumatic, hydraulic, or the like) connections, electrical connections,or other connections.

FIGS. 2A-2C depict an exploded view of the hub 100 from variousperspectives. In particular, FIG. 2A illustrates the hub 100 from astraight on side view showing the master side assembly 10 and the toolside assembly 20. Furthermore, actuator attachment portion 22-1 is shownin the tool side assembly 20. Additionally, the interface portions 11and 21 are shown. FIG. 2B illustrates the hub 100 from an angled bottomup perspective view showing the master side assembly 10 and the toolside assembly 20. Furthermore, actuator attachment portion 22-1 and 22-2are shown in the tool side assembly 20. FIG. 2B illustrates the hub 100from an angled bottom up perspective view showing the master sideassembly 10 and the tool side assembly 20. Furthermore, actuatorattachment portion 22-1 and 22-2 are shown in the tool side assembly 20.Additionally, the interface portions 11 and 21 are shown. FIG. 2Cillustrates the hub 100 from an angled top down perspective view showingthe master side assembly 10 and the tool side assembly 20. Furthermore,actuator attachment portion 22-1 and 22-2 are shown in the tool sideassembly 20. Additionally, the interface portions 11 and 21 are shown.

It is to be appreciated, that areas of the interface portions 11 and 21are depicted in FIG. 1 and FIGS. 2A-2C. However, the interface portionsmay have a variety of configurations and the interface portion shouldnot be limited by that depicted in FIG. 1 and FIGS. 2A-2C.

FIGS. 3A-3E depict an assembled view of the hub 100 and attachedactuators 30 from various perspectives. In particular, FIG. 3Aillustrates the hub 100 from a straight on side view showing the masterside assembly 10 and the tool side assembly 20. Furthermore, actuators30-2 and 30-3 are shown attached to the tool side assembly 20. Actuators30-2 and 30-3 are depicted in a “neutral” position (e.g., not inflated,deflated, or the like). FIG. 3B illustrates the hub 100 from a straighton side view showing the master side assembly 10 and the tool sideassembly 20 and the attached actuators 30-2 and 30-3 in an inflatedstate. FIG. 3C illustrates the hub 100 from an angled side view whileFIGS. 3D and 3E show the hub 100 from an angled bottom up and tom down(respectively) perspective view. In particular, the assemblies 10 and 20are shown coupled together with actuators 30-1, 30-2, 30-3, and 30-4attached to the tool side assembly and depicted as inflated.

Accordingly, the hub assembly 100 can be used to quickly switch betweenvarious grasper assemblies by changing the tool side assembly 20.Example grasper assemblies are now described. It is important to note,that a system may be implemented with one master side assembly 10 andmultiple the tool side assemblies 20 each with a different grasperconfiguration. As such, the system can be quickly reconfigured and usedto perform different operations needing different graspers or softactuators.

FIGS. 4A-4D depict an example of the hub assembly 100 including a twistlock interface. In particular, FIG. 4A illustrates an exploded top downperspective view of the hub assembly 100 showing the master sideassembly 10 and the tool side assembly 20. Furthermore, actuatorattachment portions (e.g., 22-1) are shown in the tool side assembly 20.Furthermore, details of the interface portions 11 and 21 are shown. Inparticular, the interface portion 11 includes pegs 15 and connectionport 16 while the interface portion 21 includes slots 25 and connectionport 26. The pegs and the slots are configured to be releaseably securedto each other. In particular, the slots 25 may have a varying diameter,where one end of each slot is proportioned to receive an end of acorresponding one of the pegs 15. Once the pegs 15 are fit into theslots 25, either the assembly 10 or the assembly 20 may be twisted tolock the pegs 15 in place, thereby securing the assembly 10 to theassembly 20.

FIGS. 4B-4C illustrate a top perspective and a top down (respectively)view of the tool side assembly 20. As can be seen, the tool sideassembly 20 includes actuator attachment portions (e.g., 22-1), slots25, and connection port 26. FIG. 4D illustrates a side view of the toolside assembly 20. As can be seen, the tool side assembly 20 may includea top stepped or recessed portion 23 configured to fit into acorresponding recessed portion in the interface portion 11 of the masterside assembly 10.

Additionally, the connection ports 16 and 26 may seal or form a sealwhen the assemblies 10 and 20 are secured together. As such, a sealedpathway or connection point for inflation lines (e.g., pneumatic,hydraulic, or the like) as well as electrical signal lines can beprovided through the connection points 16 and 26.

Alternatively or in addition, the tool side assembly 20 may be securedto the master side assembly 10 through a magnetic interface, anelectrostatic adhesion interface, or any other suitable type ofinterface.

The hub may be adjustable in a number of ways in order to adjust theangle of the actuators and/or the relative distance between theactuators. Exemplary embodiments of such hubs and actuators are nextdescribed.

Angular and Relative Distance Adjustment

Adjustable hubs may allow for the pitch spread, number, or type ofactuators to be actuated or adjusted. Such hubs may allow for the angleof actuators to be changed relative to one another, or for actuators tobe moved linearly relative to one another to thereby adjust the spacingbetween actuators. The adjustment of these parameters may be performedautomatically, using a control device, or manually in response tomanipulation by an operator. In either case (automatic or manualadjustment), the adjustment may be performed dynamically, without theneed to remove the actuator from the hub or to replace the actuator witha different actuator having different characteristics.

FIGS. 5A-5C illustrate an example hub assembly 100 and an exampleconfiguration of soft actuators 30-1, 30-2, 30-3 that include anelectro-mechanical portion 31-1, 31-2, 31-3. As shown, theelectro-mechanical portion 31-1, 31-2, 31-3 can be activated to rotatean actuator inwards towards the center of the hub assembly 100 oroutward away from the center of the hub assembly 100. By changing theangle of the electro-mechanical portion 31-1, 31-2, 31-3 relative to thehub assembly 100, the angle of the actuators can be changed relative tothe hub assembly 100 and therefore relative to each other. Theelectromechanical portions 31-1, 31-2, 31-3 can be used to modify and/oradjust the angle of attack of the actuators from when they are in theneutral position (e.g., refer to FIGS. 5A-5B) to when they are in theinflated position (e.g., refer to FIG. 5C). By adjusting the angle ofattack, the actuators can be configured to grasp objects of varyingsizes or configurations.

Alternatively or in addition to an electro-mechanical portion 31-1,31-2, 31-3 (e.g., a motor), the portion of the apparatus that adjuststhe angle of the actuators may be mechanical (e.g., a hand-drivencrank), fluidic (e.g., hydraulic or pneumatic, such as apneumatically-driven rotational actuator), or any combination of theseor other suitable adjustment techniques.

FIGS. 6A-D depict another example of a soft robotic actuator assembly2700 in which a plurality of actuators 2702 a, 2702 b, 2702 c, and 2702d are mounted to a hub 2704 in an angularly adjustable manner. Forexample, referring to FIG. 6A, the actuators 2702 a-d are shown in aneutral configuration, in which the actuators 2702 a-d are disposed in asubstantially parallel relationship with one another. FIG. 6B depictsthe actuators 2702 a-d in the neutral configuration of FIG. 6A with theactuators 2702 a-d pressurized (i.e., curved and grasping) to define agenerally enclosed space Sn within the actuators 2702 a-d. FIG. 6Cdepicts the actuators 2702 a-d in an angularly adjusted configuration,in which the actuators 2702 a-d have been pivoted about their respectivepoints of attachment to the hub 2704 to deflect the actuators 2702 a-dby respective angles θ_(a), θ_(b), θ_(c), and θ_(d) relative to alongitudinal axis y of the hub 2704. The actuators 2702 a-d are eachshown deflected to an angle of about 30 degrees, though it iscontemplated that the actuators 2702 a-d can be deflected to any desiredangle (e.g., between 0-180 degrees). FIG. 6D depicts the actuators 2702a-d in the angularly adjusted configuration of FIG. 6C with theactuators 2702 a-d pressurized (i.e., curved and grasping) to define agenerally enclosed space Sa within the actuators 2702 a-d. As can beseen, the enclosed space Sa defined by the angularly adjustedconfiguration of the pressurized actuators 2702 a-d is larger than theenclosed space Sn defined by the neutral configuration of thepressurized actuators. Angular adjustment of the actuators 2702 a-d maytherefore be useful for dynamically configuring the assembly 2700 forapproaching and grasping items of various sizes and geometries.

It is contemplated that the angular adjustment of the actuators 2702 a-dmay be effectuated automatically (e.g., via actuation of one or moreservo motors 2714-1, 2714-2 attached to the hub 2704 and the actuators2702 a-d) or manually. It is further contemplated that the angularadjustment of the actuators 2702 a-d may be interdependent, such asthrough a gearing arrangement having gears 2708-1, 2708-2, whereby theangles of deflection θ_(a), θ_(b), θ_(c), and θ_(d) are always equal.Alternatively, the angles of deflection θ_(a), θ_(b), θ_(c), and θ_(d)may not necessarily be always equal, but may nonetheless be dependent oneach other as a result of different gear ratios provided between thegears 2708-1, 2708-2 of the adjustment mechanisms 2706-1, 2706-2 foreach actuator (e.g., changing the angle of actuator 2702 a to θ_(a) mayhave the effect of changing the angle of actuator 2702 b to 2θ_(a)). Inlieu of gears 2708-1, 2708-2, other mechanical options for adjusting theangles of deflection in a dependent manner may be used, such as a belt2710 or cam 2712 system. It is further contemplated that the angularadjustment of the actuators 2702 a-d may be independent, whereby one ormore of the angles of deflection θ_(a), θ_(b), θ_(c), and θ_(d) may bedifferent from the others in such a way that the respective angles ofthe actuators do not depend on each other. It is further contemplatedthat one or more of the actuators 2702 a-d may be removed from the hub2704, or that one or more additional actuators may be attached to thehub 2704 for varying the configuration of the assembly 2700 to betteraccommodate grasping items of various sizes and geometries.

In other embodiments, the tool-side assembly 20 and/or the softactuators 30 may include components allowing the actuator spread to beadjusted. For example, FIGS. 7A-7E depict an example of the tool sideassembly 20 and attached soft actuators 30. In some examples, a toolside assembly 20 may be provided with the soft actuators depicted inthis example to adjust the angle of attack for picking up object.

FIG. 7A illustrates the tool side assembly 20 and the soft actuators30-1, 30-2 from various angles and perspectives. As depicted, the softactuators 30-1, 30-2 include soft angle adjustors 32-12. FIG. 7Billustrates a bottom view of the tool side assembly 20 with the softactuators 30-1, 30-2 attached and a magnified view 200 of the soft angleadjustors 32-12. As can be seen, the soft angle adjustors 32-12 aredisposed laterally between the soft actuators 30-1, 30-2. Duringoperation, the soft angle adjustors 32-12 can be independently inflatedand deflated (e.g., independent from each other and/or independent fromthe soft actuators) to adjust the angle between the soft actuators 30-1,30-2.

FIG. 7C-7E illustrate the soft actuators 30-1, 30-2 and soft angleadjustors 32-12 in various states. In particular, FIG. 7C illustratesthe soft actuators 30-1, 30-2 in a neutral position and the soft angleadjustors 32-12 deflated. As such, the angle between pairs of the softactuators 30-1, 30-2 (e.g., between 30-1 and 30-2 and between 30-3 and30-4, or the like) is reduced. FIG. 7D illustrates the soft actuators 30in a neutral position and the soft angle adjustors 32 inflated. As such,the angle between pairs of the soft actuators 30 (e.g., between 30-1 and30-2 and between 30-3 and 30-4, or the like) is increased. FIG. 7Eillustrates the soft actuators 30 in an inflated position and the softangle adjustors 32 inflated. As such, the angle between pairs of thesoft actuators 30 (e.g., between 30-1 and 30-2 and between 30-3 and30-4, or the like) is increased and the angle of attack of the inflatedsoft actuators 30 is also increased.

Although FIGS. 7A-7E depict an example in which the spread is beingchanged by the action of a soft actuator, one of ordinary skill in theart will recognize that other methods for changing the spread are alsopossible. For example, in some embodiments, a spring may hold theactuators apart. The spring may be connected to a locking crankmechanism that works in operation to the spring. When operating thecrank in one direction, the crank compresses the spring to bring theactuators together; when operating the crank in the opposite direction,the crank releases the spring to bring the actuators apart.

In other embodiments, other mechanical, electromechanical, or pneumaticdevices may be used to change the spread of the actuators.

Rigidizing Layer

Further embodiments provide an anisotropic reinforcement baseincorporating one or more rigid components such as slats. The componentsmay be made of metal, plastic, or any other suitably rigid material. Therigid components may be strapped, wrapped, adhered, or molded directlyinto the actuators to prevent bowing in the strain limiting layer, whichmakes it more difficult for the actuator to bend in a positive direction(toward a gripped object) when pressure is applied. The rigid componentsalso serve to prevent cavitation of a grip surface, which makes itdifficult to bend in a negative direction when a vacuum is applied. Inthis case, the rigid components may be molded into or adhered onto thefingers, in order to prevent the cavitating surface from pulling awayfrom the slats.

More specifically, some actuators incorporate elastomers of differingstiffness or wall thickness to accommodate a certain desired behavior.This layer of varying thickness or stiffness is sometimes referred to asa strain limiting layer.

Turning to FIGS. 8A-8F, reinforced actuators for preventing bowing in astrain limiting layer are now described. The strain limiting layer of asoft actuator can have the tendency to bow away from the neutral bendingplane of the actuator during inflation. This bowing of the strainlimiting layer increases the second moment of area of the actuatorscross section thereby increasing the actuators resistance to bending.This behavior diminishes the function of the actuator.

This problem can be mitigated by overmolding rigid elements (e.g.plastics, metals, ceramics, or stiffer elastomers) in to the strainlimiting layer. This is accomplished by placing a plurality of rigidelements into the strain limiting layer where the long axis of eachelement is oriented perpendicular to the neutral axis of bending. Thisorientation allows the rigid elements to prevent bowing of the strainlimiting layer in the direction perpendicular to the neutral axis butonly minimally impedes bending along the neutral axis.

The rigid elements may be held in place between the strain limitinglayer of the soft actuator body and an overmolded encapsulatingelastomer layer. FIG. 8A depicts side-by-side bottom views of a softactuator body 3001 without an encapsulating elastomer layer on thestrain limiting layer 3002 (left), and the same soft actuator bodyhaving an encapsulating elastomer layer 3003 (right). The encapsulatingelastomer layer 3003 may be made of the same materials as the softactuator body (e.g., the same elastomer materials), or may be made of arelatively more rigid material. FIG. 8B depicts side-by-side side viewsof the soft actuator body 3001 with and without the encapsulatingelastomer layer 3003 on the strain limiting layer 3002 (top and bottom,respectively).

In some embodiments, the encapsulating elastomer layer 3003 may overlayreinforcing slats 3004 in order to prevent bowing in the strain limitinglayer 3002. The soft actuator body 3001 may be provided with moldedtrenches 3005 for receiving the reinforcing slats 3004. Alternatively orin addition, the molded trenches 3005 may be located in theencapsulating elastomer layer 3003, or trenches 3005 may be located bothin the soft actuator body 3001 and the encapsulating elastomer layer3003. In assembly, the reinforcing slats may be slotted into thetrenches 3005 and overlaid with the encapsulating elastomer layer 3003.The slats 3004 may be made of a relatively rigid material or materialsas compared to the soft actuator body 3001, such as plastics, metals,ceramics, or stiffer elastomers.

FIG. 8C depicts the side of the soft actuator body 3001 having anencapsulating elastomer layer 3003, and FIG. 8D is a cross-sectionalview of the actuator depicted in FIG. 8C, showing the location of therigid slats 3004. FIG. 8E is an exploded view showing the rigid slats3004 between the strain limiting layer 3002 and the encapsulatingelastomer layer 3003.

FIG. 8F depicts an example of a soft actuator body 3001 having anencapsulating elastomer layer 3003, and furthermore having overmoldedrigid or elastomeric structures 3007 for reinforcing the accordiontroughs 3006 of the soft actuator bladder. The structures 3007 serve tominimize or reduce strain at the accordion troughs 3006. The pressure ofinflation of the soft actuator body 3001 may cause the troughs 3006 ofan accordion-shaped soft actuator to strain. This generates points ofstress concentration in the troughs 3006 which at elevated pressure canlead to the failure of the actuator. Nonetheless, elevating theinflation pressure of an actuator is desirable since this increases theforce that can be delivered by the actuator when it is used as part of agripper or the rigidity of the actuator when it is used as a structuralelement in an application. As a result it is desirable to reinforcethese troughs with rigid materials (e.g. plastics, metals, ceramics, orstiffer elastomers) in order to minimize the straining of the actuatorat these points when it is operated at elevated pressures.

FIG. 9A depicts an exemplary rigidizing layer 3100 that includes aplurality of rigid slats 3102 that are affixed to a flexible backing3104 in a parallel, spaced-apart relationship. The slats 3102 may beformed of any suitably rigid material, including, but not limited to,various metals, plastics, and composites. As shown in FIG. 9B, therigidizing layer 3100 can be affixed to a grasping side of an actuator3106 (the slats 3102 are facing the actuator 3106 and are therefore notvisible in this view) using various means of attachment, such as withlaces (as shown), adhesives, mechanical fasteners, stiff O-rings (e.g.,O-rings constructed of Shore 80 A or Shore 90 A elastomer), etc. Themeans of attachment may connect across the troughs of the accordionextensions of the actuators. In some embodiments, the flexible backing3104 can be omitted and the rigid slats 3102 can be integrated into thematerial of the actuator 3106 itself (e.g., by over-molding).

With the rigidizing layer 3100 applied to the grasping side of theactuator 3106 in the above-described manner, the rigid slats 3102prevent the grasping side of the actuator 3106 from bulging or becomingconvex when the actuator 3106 is pressurized, wherein such bulging couldimpede the ability of the actuator 3106 to bend inward when attemptingto grasp an item. Moreover, the rigid slats 3102 may prevent thegrasping side of the actuator 3106 from cavitating or becoming concavewhen a vacuum is applied to the actuator 3106, wherein such cavitatingcould otherwise impede the ability of the actuator 3106 to bend outwardwhen attempting to open away from an item. Since the rigid slats 3102are spaced apart from one another and are perpendicular to thedirections in which the actuator 3106 bends during opening and closing,the rigid slats 3102 do not impede or interfere with the regularoperation of the actuator 3106.

The troughs between accordion extensions tend to be the points ofhighest stress concentration. The above-noted laces serve to preventthis region from expanding under pressure, which helps to prevent afailure of the actuator. This is achieved by preventing the actuatorfrom bulging away from a neutral bending plane.

Force Amplification

Next described are force amplification structures for amplifying theforce at the distal tip of the inflated actuator as compared to anactuator that does not employ such force amplification structures.

A force amplification structure may cause the deflectable area of theactuator to be shortened. From beam theory it is understood that, forthe same actuation pressure a shorter actuator requires more force to bedeflected the same distance as a longer actuator of equivalent crosssection. As applied to a gripping actuator, the force of gripping comesfrom the fact that the object being grasped prevents the actuator fromachieving the degree of bending that the actuator would have achieved ifthe actuator were unobstructed. Thus, the grasp target that isobstructing the actuator is effectively deflecting the actuator. Theequal and opposite force to this deflection is the force of grasping.

The force amplification structures may include a ring, cuff, cylinder,rod, accordion-like structure, etc., which hold one or more actuatorstogether and provides static or adjustable constraint along the lengthof the actuators. The force amplification structures may be attached tothe actuator(s), or made integral with the actuator(s) (e.g., by moldingthe force amplification structures into the actuator(s)). The forceamplification structures may include one or more sensors to allow theamount of force amplification to be dynamically adjusted.

Multiple force amplification structures may be combined to achievedesired force application profiles. The configuration, type, and numberof force amplification structures may be varied between actuators or maybe changed on the same actuator to achieve different force amplificationresults.

The force amplification structures may also serve to make the shortenedactuator more stable. When a gripper is accelerated or decelerated(e.g., in order to move a grasped object from one location to another),the actuators may tend to sway. In some applications, particularly whereplacement accuracy is important, swaying of the actuator may beundesirable because it becomes difficult to predict where an object maybe placed. Shorter actuators tend to sway less under the same force ofacceleration or deceleration as compared to longer actuators, because itrequires more force to deflect a shorter actuator an equivalent distanceas compared to a longer actuator having the same cross-sectional area.Therefore, by reducing the effective length of the actuators (e.g., byattaching a force amplification structure), the swaying may be reduced.Thus, shortening the actuator(s) of a gripper to the smallest possiblelength for a given gripping task at hand (e.g., by using a forceamplification band) may be useful for reducing or eliminating swayduring operation, in turn improving picking and placing accuracy.

The force amplification structure may be secured directly to the hubholding the actuators (e.g., through a mechanical connection such as oneor more beams secured to the force amplification structure and the hub).This helps to prevent the actuator as a whole from swaying by leavingonly the shortened grasping end of the actuator free to move.

The force amplification structures may also serve to stabilize one ormore actuators against twisting and/or overlapping. When picking up arelatively small object, typically only the tip of the actuator will beused to grasp the target. As a result, much of the middle and proximalportion of the actuator sits in free space, without any matterobstructing these portions of the actuator. The portions of the actuatorthat are unobstructed may have a tendency to twist or overlap with eachother, which makes it difficult to precisely control a gripper includingthe twisted or overlapping actuators.

Another advantage of the force amplification structures described hereinis that they may change the profile of an actuator, and therefore changethe degree of conformal contact between a grasped target and theactuators grasping the target. As a result, the actuators can achieve ahigher degree of surface contact with the target as compared to annon-force-amplified actuator. This increased contact means more frictionbetween the actuators and the grasped target, and in turn a better grip.Thus the force amplification structures may change the geometric profileof a gripper having one or more actuators, in order to tune the gripperto the gripping of an object of a particular shape that is not wellgrasped by an non-force-amplified structure.

FIG. 10A depicts an example of a soft robotic actuator assembly 2800 inwhich a plurality of actuators 2802 a, 2802 b, 2802 c, and 2802 d aremounted to a hub 2804, and in which a force amplification band 2806surrounds the actuators 2802 a-d. The force amplification band 2806 maybe a rigid or flexible member (e.g., formed of metal, plastic, rubber,fabric, various composites, etc.) having the general shape of a ring ora cuff (or multiple, interconnected rings/cuffs as further describedbelow). The force amplification band 2806 may surround and constrain theactuators 2802 a-d at a longitudinal position located a distance d fromthe hub 2804. By constraining the actuators 2802 a-d thusly, the momentarm of each actuator 2802 a-d is shortened and, when the actuators 2802a-d are pressurized, the normal force applied by the tip of eachactuator 2802 a-d on a grasped item is increased. The forceamplification band 2806 may therefore be used to enhance the gripstrength of the actuators 2802 a-d.

In addition to increasing the normal force exerted at the tip of eachactuator 2802 a-d, the force amplification band 2806 also constrainsoutward bowing of the actuators 2802 a-d relative one another comparedto an unconstrained configuration, thereby causing the distal portionsof the actuators 2802 a-d to take on flatter profile when theypressurized relative to when the is no force amplification band 2806 inplace. Such a flattened profile may be suitable for grasping items ofparticular sizes or geometries. Still further, the force amplificationband 2806 serves to stabilize the actuators 2802 a-d to mitigatetwisting, overlapping, and/or misalignment of the actuators 2802 a-dwhen they are pressurized.

It is contemplated that the longitudinal position of the forceamplification band 2806 along the actuators 2802 a-d can be adjustedmanually or automatically. For example, FIG. 10B depicts a forceamplification band embodied by an adjustable cuff or bellows 2900 thatcan be longitudinally extended and retracted automatically (e.g., viavarious electrical, hydraulic, or pneumatic drive mechanisms) toconstrain a group of actuators 2902 a-d at a variable longitudinalposition p.

FIG. 10C depicts a force amplification band embodied by a flexible strap3000 having a figure-8 shape that defines two loops. Each loop may beused to constrain one or more actuators in the manner described abovefor providing force amplification and/or stabilization. The forceamplification band 3000 represents a 1×2 configuration, though it iscontemplated that many other force amplification band configurations(e.g., 2×2, 1×4, 2×4, etc.) may be implemented for constraining variousnumbers and arrangements of actuators without departing from the presentdisclosure. Alternatively or in addition, the flexible strap 3000 mayhave other shapes or configurations, such as a square, circular,elliptical, or triangular shape.

Gripping Structures

In some embodiments, the soft robotic actuators may be designed with, orsupplemented with, one or more gripping structures to customize theactuators' gripping profile. This may allow the actuator to betterconform to the surface to be gripped, or to have structures or texturesthat improve the actuator's gripping capabilities.

The gripping structure may be a conformal pad or other component that iseither attached to, or integral with, the gripping-side surface of theactuator. A gripping pad may have any type of textured surface, with avariety of different frictional shear forces being possible. Differentactuators attached to the same hub may have different grippingstructures. Alternatively or in addition, the same actuator may havemultiple different gripping structures located at different locations onthe actuator to allow the actuator to grip an object in a desiredmanner. The number, type, and configuration of gripping structures maybe selected based on a size, shape, or texture of an object to begripped.

FIG. 11A depicts a soft robotic actuator assembly 3200 in which a twoactuators 3202 a and 3202 b are mounted to a hub 3204, and in which theactuators 3202 a and 3202 b are provided with respective gripping pads3206 a and 3206 b. The gripping pads 3206 a and 3206 b may be integralwith actuators 3202 a and 3202 b (i.e., formed as parts of the actuators3202 a and 3202 b) or may be removably affixed to the actuators (e.g.,with mechanical fasteners, adhesives, etc.), and may have a shape, anarrangement, a texture, and/or may be formed of a material that isadapted to enhance the ability of the actuators 3202 a and 3202 b tograsp and hold particular items.

In the example shown in FIG. 11A, the gripping pads 3206 a and 3206 bmay be formed of a resilient, compressible material (e.g., foam rubber)and may each have a gripping surface that is convex when the actuators3202 a and 3202 b are not pressurized (i.e., when the actuators 3202 aand 3202 b are substantially straight). However, when the actuators 3202a and 3202 b are pressurized as shown in FIG. 11B, the flexed actuators3202 a and 3202 b may compress the gripping pads 3206 a and 3206 b andthereby cause the gripping surfaces to become substantially flat andparallel, which may be advantageous for gripping substantially planaritems such as books.

FIGS. 11C-11D depict additional, non-limiting examples of actuatorshaving gripping pads of various shapes and configurations. As previouslystated, the gripping pads may, in addition to having various shapes andconfigurations, be provided with various surface textures (ridged,waffled, concentric circular, diamond, etc.) or shapes (e.g., hook,wedge, etc.) that may assist in gripping particular items.

FIG. 11E depicts a further example of an actuator having a grippingstructure in the form of a needle or other relatively long and thinpin-like structure. The needle may allow the actuator to grip arelatively soft food item, such as a cupcake, dough ball, or cheese ballby inserting the needle into the food item in order to lift the fooditem with the actuator. The needle may be overmolded into the tip of theactuator, or may be attached to a wrap that at least partially surroundsthe actuator. Although FIG. 11E depicts a single needle, an actuator maybe provided with multiple needles mounted in any suitable configuration.

Terminology

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralelements or steps, unless such exclusion is explicitly recited.Furthermore, references to “one embodiment” of the present invention arenot intended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features.

While the present invention has been disclosed with reference to certainembodiments, numerous modifications, alterations and changes to thedescribed embodiments are possible without departing from the sphere andscope of the present invention, as defined in the appended claim(s).Accordingly, it is intended that the present invention not be limited tothe described embodiments, but that it has the full scope defined by thelanguage of the following claims, and equivalents thereof.

The invention claimed is:
 1. An apparatus comprising: one or more softrobotic actuators, the soft robotic actuators comprising: a hollow bodyincluding an elastomeric material, the hollow body configured to acceptan inflation fluid, a proximal end having an opening for receiving theinflation fluid, and a distal end opposite the proximal end that forms agripping tip; and an angular adjustment device comprising one or moresoft angle adjustors disposed adjacent to the proximal end of the one ormore soft robotic actuators, the soft angle adjustors comprising one ormore accordion extensions extending towards the distal end of the softrobotic actuators and being configured to be inflated independently ofthe soft robotic actuators.
 2. The apparatus of claim 1, wherein thesoft angle adjustors comprise a plurality of soft angle adjustors thatare further configured to be inflated independently of each other. 3.The apparatus of claim 1, wherein the soft angle actuators areconfigured to, upon inflation, adjust a spread of the soft roboticactuators.
 4. The apparatus of claim 1, wherein the soft angle actuatorsare configured to, upon inflation and upon inflation of the soft roboticacutators, adjust an angle of attack of the soft robotic actuators. 5.The apparatus of claim 1, wherein the one or more soft robotic actuatorscomprise a pair of actuators, and the angular adjustment device isprovided laterally between the proximal ends of the pair of actuators.6. The apparatus of claim 1, wherein the one or more soft roboticactuators comprise first and second actuators arranged in a first pair,and third and fourth actuators arranged in a second pair, and theangular adjustment device comprises a first soft angle adjustor betweenthe first pair of actuators, and a second soft angle adjustor betweenthe second pair of actuators.
 7. The apparatus of claim 1, furthercomprising a tool side assembly attached to the proximal end of the oneor more soft robotic actuators.
 8. The apparatus of claim 7, wherein thetool side assembly comprises an interface configured to mate to acorresponding interface on a master side assembly.
 9. The apparatus ofclaim 7, wherein the tool side assembly provides a seal for an inflationline configured to inflate the one or more soft robotic actuators. 10.The apparatus of claim 7, wherein the tool side assembly provides anelectrical connection.
 11. A method comprising: providing the apparatusof claim 1; and inflating the one or more soft robotic actuators tocause the one or more soft robotic actuators to curl and make contactwith a target object.
 12. The method of claim 11, further comprisinginflating the angular adjustment device.
 13. The method of claim 12,wherein inflating the angular adjustment device is performedindependently of inflating the one or more soft robotic actuators. 14.The method of claim 12, wherein the angular adjustment device comprisesa plurality of soft angle adjustors and inflating the angular adjustmentdevice comprises inflating the plurality of soft angle adjustorsindependently of each other.
 15. The method of claim 11, furthercomprising deploying a force amplification device at least partiallyaround the one or more actuators, the force amplification deviceconfigured to amplify a force exerted at the distal end of one or moreactuators as compared to actuators that do not employ the forceamplification device.
 16. The method of claim 15, wherein the forceamplification device comprises a cuff or bellows at least partiallysurrounding the one or more soft robotic actuators at a location betweenthe proximal end and the distal end, the cuff or bellows having alongitudinally-extendible length, and further comprising adjusting thelength of the cuff or bellows to change an amount of force exerted atthe distal end of the one or more soft robotic actuators.
 17. The methodof claim 11, further comprising attaching a strain limiting layer to theapparatus, wherein the soft robotic actuator has a neutral axis ofbending, and the strain limiting layer comprises a rigidizing layerhaving one or more rigid components oriented perpendicular to theneutral axis of bending.
 18. The method of claim 17, further comprisingsecuring the rigidizing layer to an actuator with one or more laces,straps, rings, or cords that extend across one or more troughs on anon-grasping side of the actuator.
 19. The method of claim 11, whereinthe apparatus further comprises a tool side assembly having aninterface, and further comprising attaching the tool side assembly to amaster side assembly by mating the interface of the tool side assemblyto an interface of the master side assembly.
 20. The method of claim 19,further comprising supplying an inflation fluid to the apparatus via theinterface on the tool side assembly.